Use of Radon Measurements for Evaluation of Volatile Organic Compound (VOC) Vapor Intrusion
Abstract
We have utilized a simple method for the collection of gas samples from vapor intrusion investigation sites and the analysis of radon concentrations at an offsite laboratory. The radon data can be used to evaluate the movement of soil gas through building foundations at sites contaminated with volatile organic compounds (VOCs) where vapor intrusion is a concern. The use of radon as a tracer for the movement of soil gas into buildings minimizes the problem of indoor sources associated with the direct measurement VOCs. We have used this method to measure indoor to sub-slab attenuation factors in six buildings with the resulting values ranging from 0.0002 to 0.006 (dim). These values are similar to radon attenuation factors reported by other researchers, but are much lower than default values for VOCs recommended in regulatory guidance (United States Environmental Protection Agency USEPA, 2002). The vertical radon concentration profile in soil gas can be used to evaluate soil gas mixing with the atmosphere to support the collection of soil gas samples for VOC analysis adjacent to, rather than below, a building.